The present invention relates to a device and method for the detection of and differentiation between cancerous and noncancerous tumors in human and animal tissue, and especially in human breasts where the invention has its most useful and important application.
Present methods of interrogating human tissue to detect the internal structure underlying the skin have employed various x-ray, computerized axial tomographic x-ray, thermographic, and ultrasonic wave techniques. While x-rays yield good images of internal body structure, they rely on ionizing radiation which entails a carcinogenic risk to the patient. This risk is of special importance in the detection of breast lesions. Wholly apart from the radiation dosimetry risks associated with the use of x-rays, the utilization of x-rays is poor in terms of tissue contrast and provides no physiological information.
The use of thermographic techniques in the interrogation of human tissue, which detects the differences in temperature in the different tissue types in the body portions examined, uses infrared radiation detectors to detect the different degrees of infrared radiation emitted by heated bodies. Thermography has a number of shortcomings which make it unsatisfactory as a diagnostic tool, particularly in the case of human breast lesions. Thus, thermography has the disadvantage of being unable to detect and locate small non-palpable lesions in the thick living tissues such as the human breast because insufficient infrared radiation is generally emitted by such small bodies to enable the infrared sensing unit of such equipment to detect any appreciable difference in tissue temperature caused by such small bodies. Temperature fluctuations in overlying skin are large relative to the small temperature difference arising from a tumor. Thus, in the case of breast lesion detection, thermography, alone, generally is not relied upon, and is usually used in conjunction with x-ray mammography. Poor contrast and minimal physiological information are the fundamental shortcomings of thermography. Thus, thermography has been generally discredited as a diagnostic technique because of the very faint signal generated by tumors as compared with the much greater noise signals caused by temperature fluctuations generated by the overlying skin.
Ultrasonic techniques are limited in application by attenuation and interaction of ultrasound waves with the tissue being interrogated. Differentiation of cystic from solid lesions is the primary utility of ultrasound. In addition, ultrasound poses certain biological hazards such as platelet aggregation which is exhibited at power levels less than those causing thermal injury. The primary limitation of ultrasound is poor image quality.
In summary, ionizing X-rays produce good quality images of well developed tumors without adequate substantial contrast differentiation between cancerous and non-cancerous tumors and between such tumors and normal tissue, ultrasound produces fair to poor images and thermography produces only very poor images thereof.